Control device



Dec, 24, 1940. K. CLARK 2,225,982

CONTROL DEVICE Original Filed Jan. 3, 1938 HHHRR'iL INVENTOR.

KENDALL CLARK ATTORNEYZS Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE CONTROL DEVICE Kendall Clark, Dayton, Ohio, assignor to International Engineering Corporation, Chicago, 111., a corporation of Illinois 11 Claims.

to the "hot" side and a delayed action on re-.

15 turning to the cold side, whereby the burner is prevented from going on again until the furnace has cooled substantially.

Important features of novelty relate to the structure of the stack switch, as well as its arrangement in the control circuit. These features, and various other structural ieatures and desirable arrangements, will be apparent from the following description of the illustrative embodiments shown in'the accompanying drawing,

in which:

Figure 1 is a l'ongitudinarsection of my novel stack switch;

Figure 2 is a transverse section on the line 2-4 of Figure 1; a

Figure 3 is a partial exploded view showing in detail several elements of my novel switch; and

Figure 4 is a wiring diagram a novel oil burner control circuit using resistance ignition and my novel switch and adapted to control a splitphase induction motor.

Referring to Figure 1 oi the drawing there is shown a chimney or stack l0 through which the gases 0:! combustion from an oil burner are adapted to pass. The oil burner may be of any 40 type such as, tor example, that shown in my copending application Serial No. 117,459, filed December 24, 1936, in which a motor is adapted to actuate a fan and fuel pump to supply a combustible mixture of oil and air to a furnace and in which the starting of the motor immediately,

or at least within a very short time, starts the flow of combustible mixture.

My novel stack switch indicated generally by the numeral I2, is mounted on the stack by means such as a flanged fitting bolted thereto and having a circular opening coincident with an opening in the stack through which passes a tubular member l8 removably secured in the flange I by any desired means, such as a set screw l8, so that one end is inside the stack and the other outside.

A flattened portion N on the inside end of the tube i8 provides a seat to which is riveted or welded one end 01 a helical bi-metallic element 22 oi less diameter than the tube It so that the switch may .be removed bodily irom the stack by loosening the set-screw I8 and withdrawing the switch from the flange l4.

Threaded into the outer end oi the tube II is a combination bolt and bushing N having a head between which and the tube ii are compressed: flrst, the bottom of a cup-shaped switch housing 26; and second, a series of heat radiating fins 28 preferably of copper, fitting tightly to the bushing and spaced by washers 30 of any suitable non-heat-conducting material.

In the bushing 24 is Journalled a long shaft 32 having formed on its inside end (i. e. inside the stack) a slot 34 (Fig. 3) adapted to receive and have secured therein the bent in, free end of the bimetal helix 2!, and having at its other end, projecting into the switch housing 26, first a squared portion It; and second, a cylindrical pin 38.

The squared portion 36 engages a clutch to be described below, and the pin 38 iorms a bearing for one end oi a shait 40, the other end of which is provided with a portion 42 oi! decreased diameter Journalled in a closure 44 for the open end of the cup. This closure is preferably made 0! electrical insulating material.- The central part 01' the shaft 40 is supported by an insulating partition 43 separating the switching elements from the clutch elements previously mentioned. The shaft 40 is preferably made of Bakelite or other insulating material.

A switch arm 46 formed 01' a strip of brass or the like having contact points 48 secured on onposite faces adjacent one end and having its other end i'ormed parti-cylindrically, passes through a slot 50 in the shaft 40. A spring 52 urges the arm radially so that the parti-cylindrical end maintains continuous contact with a main contact 54 secured to the closure 44. This contact is formed on an are having its center at the center 0! the shaft, and it has humps 68 and 58 adjacent each end of the are adapted to act as latches for the arm 6 in its respective contact engaging positions.

a The contact 54 is secured to the closure 44 by means of a rivet Eli having a long prong on the outer end adapted to receive a plug-in socket or the like 02, and similar rivets 84 and 88, also adapted to coact with the socket, carry contacts 68 and I0 respectively which engage with the contacts 48 in opposite positions of the switch arm. The contacts 68 and I0 are resiliently mounted by means of spiral springs I2 secured in the inside projections of the rivets 84 and 86 respectively.

Another contact I4 is mounted on a support "I6 secured in the rivet 66 which passes over the switch arm 46 so that the contact is positioned directly behind the contact 68 permitting the switch to close and open two circuits simultaneously.

An important minor feature of theinvention is a novel slipping clutch connection between the shafts 32 and 40 comprising a C-shaped stamping 18 pierced at the back of the C with a square hole fitting on the squared portion 88 of the shaft 32 and having the arms of the C closely formed around the shaft 40 and held in tight frictional engagement therewith by a garter spring 82. This clutch permits continued expansion or extraction of the bimetallic element 22 after the switch has been operated.

In operation, when no gases are passing through the stack III the bimetal element 22 is cold and urges the arm 46 in the counter-clockwise direction so that contacts 48, 68 and I4 are closed and the parti-cylindrical end of the arm. 48 is to the right of the hump 58. The switch is now said to be on the cold side.

In this position the burner is brought into operation, and the gases of combustion passing the bimetal element 22 cause it to wind up more closely urgingthe arm 46 in the clockwise direction, but it is held in place by the hump 88 until the force'exerted is sufficient to compress the spring 82, whereupon the arm snaps to the other side closing the contacts 48 and I0, the particylindrical end of the arm 46 passing over the hump 68 which is lower than the hump 68. In this position the switch is said to be on the hot" side.

Whenever gases cease to flow in the stack the bimetal element cools and unwinds and the arm snaps in the opposite direction. An important feature of the invention resides in making the hump 88 higher than the hump 88 whereby in returning to the cold side insufficient energy is stored in the bimetal element to move the arm over the hump 88, thus creating a delay period in which the bimetal element must cool further and store up suflicient energy to lift the arm over the hump 58 before the cold side contact is made.

While the foregoing refers to a specific embodiment it is clear that a great number of variations in arrangement of contacts and delay action might be worked out for particular circuit requirements. 7

Referring now to the control-circuit diagram of Figure 4 there are shown the two wires 82 and 84 of a single-phase A. C. line. Connected in series in the line 82 is the usual room thermostat 88 of any desired type adapted to close the circuit when heat is called for, together with a limit switch 88 (adapted to open the circuit upon over-pressure in a. steam heating system or upon excessive temperature in hot air and hot water systems), and a time delay switch 90. The wire 82 terminates at the main contact 54 of the stack switch I2.

In this case the time delay switch is illustrated as a bi--metal element 82 anchored at one end and closing the circuit by a contact at its other end, a heating coil 84 on a separate circuit and a latch 86, adapted to hold the bimetal element away from the contact when deformed by the heat in the coil 94, thereby requiring manual operation to reestablish the circuit.

The other line 84 terminates at the junction of two parallel circuits one of which 85 has connected therein, in series, the running or inductive winding 88 of a split phase induction motor I00 which operates the fuel pump and fan (not shown) of the oil burner. The wire 85 terminates at the prong 66 of the stack switch and is thus connected to both contacts I0 and I4 so that contact is made with it on both the hot" and cold sides of the swtich.

The other parallel circuit I02, connected to the line wire 84, has connected in series in it a resistance ignition element I04 which may be of the type described below, the starting or split phase winding I06 of the motor I00 and the heating coil 84 of the time delay switch 80. The

line I02 terminates at the contact 68 of the stack switch.

It will be noted that instead of employing the usual resistance winding in the splitphase coil, whereby energy is wasted, the ignition and delay switch resistances are substituted thereby causing the heretofore wasted energy to serve a use ful purpose.

In operation, assuming the room thermostat to be open, the stack switch will be on the cold" side with the contact 48 in engagement with contacts 68 and I4. As the space to be heated grows colder, the room thermostat 86 closes the circuit 82 and current flows through both circuits 88 and I02 energizing the starting and running windings I06 and 88 of the motor I00 and thereby starting the motor to supply the combustible mixture to the furnace.

At the same time the ignition element I04 is heated by the current in the circuit I02 and ignites the mixture. With combustion established, the hot gases in the stack I0 gradually heat up the bimetallic element 22 until the switch snaps to the hot" side. This opens both circuits 88 and I02 but instantaneously reestablishes circuit 85 through the contact It and the motor I00 continues to run, energized solely by the running" winding 98 in the manner of a simple single phase induction motor.

When the space being heated is warm enough the room thermostat 88 breaks circuit 82 stopping the motor. The gases in the stack gradually cool of! permitting the switch I2 to return to the cold side.

If the current should only be interrupted long enough for the motor to stop and then reestablished the motor could not start until the furnace has cooled and the stack switch snapped back to the cold" position whereupon ignition is supplied and the burner restarts in the normal manner. The motor refuses to startuntil both the starting and running windings are energized. If combustion fails to take place the continued flow of the heavy starting current through the separating contacts I0 and 48 and then return 75 the switch to the cold side to restart the burner. The previously described delay in returning permits the furnace to cool tothe point where it is safe to restart without danger of explosion in event that the continued running of the motor, while the stack switch was cooling off enough to open the circuit 85, has resulted in discharging a lot of oil into the furnace. Upon restarting, if the condition which caused failure of combustion has not been remedied, the time delay switch will lock. out the system. I

It will be noted that this system employing my novel stack switch provides intermittent ignition providing long-life for the ignition element.

While only one embodiment of my invention has been described in detail, it is not my intention that the scope of the invention should be limited.

to that embodiment or otherwise than by the terms of the appended claims.

This application is a division of Patent No. 2,180,580 granted Nov. 21, 1939. v

I claim:

1. A control device for an oil burner or the like comprising a thermostatically-operated shaft, a contact member mounted on and movable radially with respect to said shaft, a cylindrical contact against which the end of said member bears, a spring yieldingly urging said member radially of the shaft against the cylindrical contact, said cylindrical contact having humps at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, and

spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over 2. A control device for an oil burner or the like comprising a thermostatically-operated shaft, 9. contact member mounted on and movable radially with respect to said shaft, a cylindrical contact against which the end of said member bears, 'a spring yieldingly urging said member radially of the shaft against the cylindrical contact, said cylindrical contact having humps of different heights at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, the force to carry said member over the lower hump in the direction of the higher one being insufficient to carry it over the higher one until additional torque is built up on the shaft, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

3. A control device for an oil burner or the like comprising a thermostatically-operated shaft, a contact member mounted on and movable radially with respect to said shaft, a cylindrical contact against which the end of said member bears, a spring yieldingly urging said member radially of the shaft against the cylindrical contact, said cylindrical contact having humps at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, and. spaced contacts engageable by the contact member and one of which is enthe other of said humps to the outer side theregaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof, together with a third contact electrically connected to one of the spaced contacts and closed by engagement with said contact member at the same time as the other of the spaced contacts.

4. A control device for an oil burner or the like comprising a thermostatically operated shaft, a contact member mounted on and movable radially with respect to said shaft, a cylindrical contact against which the end of said member bears, a spring yieldingly urging said member radially of the shaft against the cylindrical contact, said cylindrical contact having humps of different heights at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, the force to carry said member over the lower hump in the direction of the higher one being insuflicient to carry it over the higher one until additional torque is built up on the shaft, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof, together with a third contact electrically connected to one of the spaced contacts and closed by engagement with said contact member at the same time as the other of the spaced contacts.

5. A control device for an oil burner or the like comprising a thermostatically-operated shaft, 9. contact member mounted on and movable radially with respect to said shaft, a cylindrical surface against which the end of said member bears, a spring yieldingly urging said member radially of the shaft against the cylindrical surface, said cylindrical surface having humps at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

6. A control device for an oil burner or the like comprising a thermostatically-operated shaft, 9, contact member mounted on and movable radially with respect to said shaft, a cylindrical surface against which the end of said member bears, a spring yieldingly urging said member radially of the shaft against the cylindrical surface, said cylindrical surface having humps of different heights at opposite sides over which the shaft suddenly forces the contact member when the torque on the shaft builds up enough to overcome said spring, the force to carry said member over the lower hump in the direction'of the higher one being insufficient to carry it over the higher one until additional torque is built up on the shaft, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

7. A switch comprising a shaft, resilient means for urging the shaft in opposite directions at different times, a member carried by the shaft and radially movable thereon, a fixed cylindrical surface engaged by the member, a spring urging the member against the surface, spaced humps on the surface over which the shaft forces the member when the torque on the shaft is sufficient to overcome said spring, an electrical contact mounted on the shaft, and spaced contacts engageable by the first na med contact and one of which is engaged thereby when said member is forced over one of'said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

8. A control device for an oil burner or the like comprising a thermostatically-operated shaft, a second shaft, slipping clutch means connecting the two shafts, a contact member mounted on and movable radially with respect to said second shaft, a cylindrical contact against which the end of said member bears, a spring yieldingly urging said member radially of the second shaft against the cylindrical contact, said cylindrical contact having humps at opposite sides over which the second shaft suddenly forces the contact member when the torque on the second shaft builds up enough to overcome said spring, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over one of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

9. A control device for an oil burner or the like comprising a thermostatically-operated shaft, a second shaft, slipping clutch means connecting the two shafts, a contact member mounted on and movable radially with respect to said second shaft, a cylindrical contact against which the end of said member bears, a spring yieldingly urging said member radially of the second shaft against the cylindrical contact, said cylindrical contact having humps of different heights at opposite sides over which the second shaft suddenly forces the contact member when the torque on the second shaft builds up enough to overcome said spring, the force to carry said member over the lower hump in the direction of the higher one being insufficient to carry it over the higher one until additional torque is built up on the second shaft, and spaced contacts engageable by the contact member and one of which is engaged thereby when said member is forced over on of said humps to the outer side thereof and the other of which is engaged by said member when it is forced over the other of said humps to the outer side thereof.

10. A switch comprising an element movable between two positions, contacts engaged by said element at said two positions, a surface engaged by the element including two humps each adapted to hold said element at one of the extreme positions and one of said humps being higher than the other, resilient means urging the element against said surface, and resilient means adapted to urge said element from one position to the other and vice versa, said bumps and said two resilient means being so constructed and arranged that when the element is urged over the higher one it will snap over the lower to the extreme position, but when the element is urged over the lower one in the reverse direction it will not pass over the higher one until additional force is exerted by the last named resilient means.

11. A switch comprising an element movable between two positions, contacts engaged by said element at said two positions, a surface engaged by the element, means constructed and arranged to hold said element at one of the extreme positions and having greater holding power at one extreme position than at the other to give a delayed action in one direction, resilient means urging the element against said surface, resilient thermostatic means adapted to urge said element from one position to th other and vice versa, and friction clutch means interposed between said element and the resilient thermostatic means.

KENDALL CLARK. 

